With the ever increasing goal of reducing manufacturing costs, many manufacturers of off-highway implements are designing frames and sub-assemblies which can be commonly used on more than one implement model. From a manufacturing perspective, it is beneficial to have a common frame design for a wide variety of implements. Accordingly, one power train assembly design including the stone engine and transmission combination can be used on more than one off-highway implement model. This modular design concept likewise extends to work stations or cab enclosures and furthermore to shift mechanisms used to condition the transmission of the power train assembly.
Multiple speed transmissions of the type that are used in agricultural and off-highway implements are typically arranged in combination with a self-propelled engine that is operated at a substantially constant speed. The ground speed of the implement is determined by the particular gear ratio or condition of the transmission. Transmissions of off-highway implements are typically provided with at least two speed ranges and four or more gear ratios in each speed range setting.
The range setting and speed setting for the transmission are usually made by moving separate shift levers. The shift lever is connected to suitable transfer linkage which responds to movement of the shift lever through a shift pattern to condition the transmission. Sometimes, the forward, neutral or reverse setting is determined by the position of another lever. Besides the various shift levers, off-highway implements, such as agricultural combines or cotton harvesters, are replete with other control mechanisms arranged in a cab area or other driving compartment of the implement. Accordingly, the implement operator may use one hand to condition the transmission while utilizing the other hand to control any of several other mechanisms during continuous operation of the implement.
As is well known, the speed ratio of the transmission is selected by having the operator move a shift lever through a generally horizontal H-pattern. The H-pattern defines at least three different fore-and-aft limit positions with a neutral range or position being defined by the "cross bar" of the H-shift pattern.
Although the standard horizontal H-type shift pattern is popular and widely used on a variety of off-highway implements, in some situations, for example, where the driving compartment has limited space constraints and especially where the shift lever is disposed proximate to one side wall of the driving compartment, there is not always enough room for the shift lever to move through a standard H-type shift pattern. In those situations where space constraints prohibit movement of the shift lever through a standard H-type shift pattern, and for other reasons alternative shift mechanisms may either be required or desired.
Thus, there remains a need and a desire for a transmission shift mechanism having a modular design and which is capable conditioning a transmission of an off-highway implement through a plurality of speed ratios without requiring side-to-side movement of the shift lever.